The invention relates to a process for solubilizing a ligand-free monomer/maleic anhydride polymer, and, more particularly, to a process for forming an aqueous cut of said polymer suitable for processing into a coating film having enhanced heat resistance and to the aqueous cut produced therefrom.
In U.S. Pat. No. 4,358,573, there is disclosed a method for solubilizing a terpolymer of maleic anhydride and mixtures of lower and higher alkenes employing an aqueous solution of ammonium hydroxide. However, films formed from such polymers lack enhanced heat resistance and can become tacky during storage and use.
In the past zinc ammonium carbonate has been employed as an additive to provide cross-linked emulsion polymer compositions. As illustrated in U.S. Pat. No. 4,339,370 a zinc complex was used to cross-link, but not to dissolve or disperse, a polymer. In U.S. Pat. No. 3,320,196 a zirconium complex was used to disperse certain alkali soluble resins, including rosin/maleic anhydride adducts condensed with polyols. The resulting polymers were employed in removable coating compositions exhibiting enhanced water and detergent resistance in providing high gloss and hardness.
In U.S. Pat. No. 3,308,078, a zinc ammonium acetate was employed to aid in dispersing an organic film former of a polyligand emulsion polymer of the styrene-acrylate type.
There has been a continued need for providing resin coatings imparting superior heat resistance to the article to which they are applied. Paper goods such as paper plates and cups employed for hot foods require heat resistant coatings.
Further, in the graphic arts field there exists a need for marking materials containing resin binders, such as inks and paints. Such marking materials, upon application to articles, provide information or decoration. However, until now, marking materials have not provided satisfactory resistance to the application of heat during storage or use.